Mechanical door closure devices that automatically return a double-acting door to a preferred center position are well known and are exemplified by the mechanisms illustrated and described in U.S. Pat. No. 4,951,351, issued Aug. 28, 1990 to A. Eckel; U.S. Pat. No. 4,945,606, issued Aug. 7, 1990 to A. Eckel; U.S. Pat. No. 4,124,955, issued Nov. 14, 1978 to A. J. Kochis; and U.S. Pat. No. 3,263,365, issued Aug. 2, 1966 to O. C. Eckel. Such devices are generally satisfactory, but have limitations. For one thing, they are lacking aesthetically. For another thing they comprise a cam and cam follower, and the latter requires a roller in engagement with the cam in order to allow the door to pivot freely between open and closed positions. The roller is subject to breakdown. A further limitation of the foregoing type of closure device is that return motion to center position tends to be uneven due to the contour of the cam.